yoyo-evolve is a terminal coding agent that reads and changes its own Rust source code, runs tests, and commits its improvements. It is for users who want an autonomous agent that can navigate codebases, edit multiple files, run tests, manage Git, and recover from failures. The catalogue entries are skills for working with this coding agent.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add yologdev/yoyo-evolve --skill skill-creatorgit clone --depth 1 https://github.com/yologdev/yoyo-evolveWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/yologdev/yoyo-evolve/skill-creator)<a href="https://agentmods.dev/skills/yologdev/yoyo-evolve/skill-creator"><img src="https://agentmods.dev/badge/skills/yologdev/yoyo-evolve/skill-creator/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/yologdev/yoyo-evolve/skill-creator"><img src="https://agentmods.dev/badge/skills/yologdev/yoyo-evolve/skill-creator.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Agent Snooping · line 30 Skill enumerates or reads other installed skills. Access to other skills' SKILL.md files or the skills directory reveals prompt instructions, capabilities, and secrets that should be invisible to peer skills.Fix: Remove all code or instructions that list or read other skills' files or directories. Skills should operate independently; cross-skill access is a privilege escalation.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00046 | $0.03203 |
| Opus 5.5 | $0.00018 | $0.01281 |
| Sonnet 5.5 | $0.00009 | $0.00641 |
| Haiku 4.5 | $0.00005 | $0.00320 |
Grade A, and why
skill-creator scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
- The skill content MUST be downloaded in this same session from a verifiable URL (curl/git/gh). Record the URL in the skill's body under a `## Source` section. How it starts
The opening of the file, as written. The whole thing — 255 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill Creator
You are creating a new yoyo skill on demand, in direct response to an explicit request — either from the human creator or from a community issue asking for a new capability.
skill-creator vs skill-evolve
These are complementary, not redundant. Use the right one:
| Question | skill-creator (this skill) | skill-evolve |
|---|---|---|
| Who triggers it? | Human creator OR community issue (explicit ask) | GitHub Actions cron (autonomous) |
| When does it run? | Inside a normal evolve session, on demand | Hourly cron at :30, gated by 5-session counter + 24h cooldown |
| What signals does it use? | The user's request | Past-session evidence (learnings, journal, audit-log) |
| Recurrence gate? | No (human is in the loop) | Yes (≥3 sessions for create) |
| Diff-scope guard? | None — runs in evolve session | Yes — scripts/skill_evolve.sh enforces |
| Auto-commit? | Yes (inside evolve session's commit flow) | Yes (after diff-scope + build/test gates) |
Rule of thumb: if no human asked, you're not creating a skill — you're noticing a pattern. Write it to memory/learnings.jsonl with a pattern_key and let skill-evolve pick it up on the next cycle.
When NOT to use this skill
- You're inside a
scripts/skill_evolve.shcycle. Use the Create branch inskills/skill-evolve/SKILL.mdinstead — it has the right gates (recurrence, dedup, ≤25 cap). - You noticed a recurring pattern but no one asked. Write a learning with
pattern_key; skill-evolve owns autonomous creation. - The user asked for a one-off helper that won't be invoked again. Just write it inline; don't litter
skills/.
When to use this skill
- The human creator (Yuanhao) tells you "scaffold a new skill for X"
- A community issue says "please add a skill for X" and you decide during a normal evolve session that the request is concrete enough to act on
- You're installing a third-party skill from outside the repo (uses
origin: marketplaceororigin: gh:author/repo)
Procedure
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 255 lines · 46 tokens per session scan A b9de48c43e6f
skill-creator is a skill published in the GitHub repository yologdev/yoyo-evolve (1,915 stars, last pushed today), licensed MIT. It adds 46 tokens to every session and 3,203 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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